Dialysis processes for the treatment of patients with kidney malfunction are coming into wider and wider use as more and more dialysis equipment becomes available. Dialysis processes are literally life-saving processes, but sometimes produce adverse secondary effects, such as fatigue and nausea. To reduce the adverse side effects and for other reasons, experimental work on the parameters of the process is being carried out, including investigation to improve the composition of the dialysate liquid.
Dialysate liquids must contain an alkalizing salt. In the early days of dialysis development sodium bicarbonate was used as the alkalizing agent. However, because of shelf-life and stability problems, as well as problems encountered by precipitate formation when calcium and/or magnesium salts are also present in the dialysate, sodium acetate was substituted for sodium bicarbonate as an alkalizing agent more than fifteen years ago. Even today dialysis solutions usually contain sodium acetate as the alkalizing agent. Sodium acetate solutions are more easily maintained than sodium bicarbonate solutions in a state of sterility; sodium acetate metabolizes in the bloodstream to sodium bicarbonate.
However, with the increasing acceptance and use of large surface area dialysis equipment, see Babb et al., Trans. Amer. Soc. Artif. Int. Organs XVII:81-91 (1971), evidence is accumulating that sodium acetate dialysates are not without shortcomings.
Additionally, it has been observed that patients dialyzed on large surface area dialyzers using a sodium acetate dialysate were rapidly depleted of bicarbonate ion during dialysis, thereby placing the patients in acidosis. Moreover, inasmuch as the influx rate of acetate ions into the patient's bloodstream during dialysis on a large surface area dialyzer usually is greater than the rate of metabolism of acetate ions to bicarbonate ions, a relatively large concentration of bicarbonate ions is generated after dialysis, producing alkalosis. Kirkendol et al., Trans. Am. Soc. Artif. Intern. Organs XXIII:399-403 (1977), recognized the drawbacks of sodium acetate dialysates as well as the impracticability of of sodium bicarbonate dialysates and investigated other potential substitutes for sodium acetate.
Graefe et al., in an article entitled "Less Dialysis-Induced Morbidity and Vascular Instability with Bicarbonate in Dialyzate," published in Annals of Internal Medicine 88:332-336, 1978, disclose that sodium bicarbonate-containing dialysate fluid produces less nausea, headache, vomiting, post-dialysis fatigue, hypo-tension, disorientation and dizziness than sodium acetate-containing fluid when used in a high-efficiently large-surface-area dialyzer.
A beneficial effect of sodium bicarbonate-containing dialysates in reducing incidence of atherosclerosis is recognized in Kluge et al., Int. Soc. Art. Org. 3A, p. 23 (April 1979).
These articles would suggest that sodium bicarbonate, rather than sodium acetate should be the alkalizer of choice in dialysate liquids. However, as pointed out hereinabove, sodium bicarbonate solutions present practical problems because these solutions are not bacteriostatic and thus may present sterility problems.
Aqueous sodium bicarbonate solutions, unlike aqueous sodium acetate solutions, are not self-sterilizing and cannot be prepared in advance of their use for dialysis. Common infectious organisms can survive and proliferate in sodium bicarbonate solutions; and infection of the patient is thus possible when there is even a minor and inadvertent departure from sterile technique in the handling of the dialysis process.